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  1. #include <iostream>
  2. #include <thread>
  3. #include <mutex>
  4. #include <atomic>
  5. #include <assert.h>
  6. using namespace std;
  7.  
  8. std::atomic<bool> x;
  9. atomic<bool> y;
  10. atomic<int> z;
  11.  
  12. void write_x_then_y(){
  13. 	x.store(true, memory_order_relaxed);
  14. 	y.store(true, memory_order_relaxed);
  15. }
  16.  
  17. void read_y_then_x(){
  18. 	while(!y.load(memory_order_relaxed));
  19. 	if (x.load(memory_order_relaxed)){
  20. 		++z;
  21. 	}
  22. }
  23.  
  24. int main() {
  25. 	x = false;
  26. 	y = false;
  27. 	z = 0;
  28. 	std::thread a(write_x_then_y);
  29. 	std::thread b(read_y_then_x);
  30. 	a.join();
  31. 	b.join();
  32. 	assert(z.load() != 0);
  33. 	return 0;
  34. }
  35.  
  36. void write_x_read_x_write_y(){
  37. 	x.store(true, memory_order_relaxed);
  38. 	int z = x.load();
  39. 	y.store(true, memory_order_relaxed);
  40. }
Success #stdin #stdout 0s 7564KB
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https://ideone.com/s9msQ7
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
secret

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